Hey'll
 
Will Sonar X3 scale (21:9) properly over 3440x1440 video display?  Thinking of getting one...
 

 
Hopefully does...
 
Cheers
 

Its just a guess but I believe if windows and your video card will allow the full resolution of the monitor that Sonar will not have any problems with it.

The Sonar window can be stretched to cover two side-by-side 16:9 monitors (my setup), which is an effective 32:9 setup. So, I am sure it'll work just fine on a 21:9.
The bigger issue is whether or not your graphics card can handle the 3440X1440 resolution. If your graphics card (or motherboard) is equipped to drive multiple monitors, you can probably handle a single 3440 wide screen. You should check the specs, though, and verify that your driver supports that resolution.
 

Should be fine then:
http://www.geforce.com/hardware/notebook-gpus/geforce-gt-740m/specifications
 
NVidia GForce GT 740M
 
Display Support:
YesH.264, VC1, MPEG2 1080p video decoder
Up to 3840x2160 LCD – eDP 1.2 support
Up to 1920x1200 LCD – LVDS support
Up to 2048x1536 VGA analog display Support
Up to 3840x2160 DisplayPort Multimode SupportYes HDMI 

Yes HDCP content protectionYes 7.1 channel HD audio on HDMI
Yes TrueHD and DTS-HD Audio Bitstreaming

I am also hoping to get either the 21:9 or 34 inch monitor. Does anyone have a pic of how this will translate to a screen? Thanks.